It has been known in the prior art to provide a urinal comprising a bowl surface having side sections composed of side walls which each project forwardly and inside of the urinal from respective left and right side edges of the bowl surface and a spreader provided on the bowl surface centrally at its upper region. In such conventional urinal, the flush water which is discharged by the spreader is not adapted to be positively directed at the side sections comprising the side walls of the bowl surface with a view to preventing the flush water from running off outside the urinal bowl surface.
It also has been proposed in Japanese Patent No. 5185067 (Patent Document No. 1) to provide a urinal comprising a bowl surface having outer wall portions outwardly surrounding respective opposite side sections of the bowl surface with a view to cleaning the side sections of the bowl surface. Such urinal may cause the flow of the discharged flush water to pass over the opposite side sections of the bowl surface and reach flush water spilled from the side sections to the surrounding outer wall portions, which may result in the reduction of the area of the side sections that is difficult to clean by means of the flush water.
It, further, has been known in the prior art, for example Japanese Patent Laid-Open Application 2014-70376 (Patent Document No. 2) to provide a urinal comprising a bowl surface having side sections composed of vertical side walls which each project forwardly and inside of the urinal from respective left and right side edges of the bowl surface, the bowl surface centrally at its upper region being backed rearwardly and downwardly so as to limit a splatter of the discharged flush water.